A detail of one of the working comic strip panels drawn by “Calvin and Hobbes” creator Bill Watterson for the “Pearls Before Swine” strip earlier this year that was up for sale at Heritage Auctions. This strip was the high-seller of the three, realizing $35,850.

The auction was held at Heritage Auctions, which had expected the three strips to max about at about $30,000.

Watterson’s return to the comics pages took place during a three-day run in June of this year. The comics he drew were supposedly drawn by an elementary school-aged girl who said she could draw Pastis’s comic strip better than he could. The resulting three strips feature middle panels drawn by Watterson, taking Pastis’s characters and giving them a definite Watterson/Calvin and Hobbes look.

The strips up for auction were the working pencil and ink drawings. The second of the three strips, featuring Watterson-drawn versions of Pastis’ pig and rat characters and a “Calvin and Hobbesish” giant robot attacking a city realized the most, selling for $35,850 (including the 19.5-percent buyer’s premium).

“Anytime original Bill Watterson comic art shows up for auction it’s a big deal,” said Todd Hignite, vice president at Heritage Auctions, before the auction. “His collaboration with Stephan Pastis was an unexpected treat for his millions of fans. Now, thanks to this auction, fans will get to take the original art home while raising money for a great cause.”

The collaboration between the two artists came at the suggestion of Watterson and was immediately embraced by an overwhelmed Pastis, who, like some many modern cartoonists, was greatly influenced by Watterson and Calvin and Hobbes. The trajectory of the three strip arc follows Pastis’ comic strip alter-ego as he turns the drawing of the comic over to a precocious second-grader named Libby for three days. The results are both wickedly funny and uniquely Watterson, while remaining true to the sharp humor that defines the Pearls Before Swine strip.

At Watterson’s request, the artwork is being sold on behalf of Team Cul de Sac, a non-profit charity established by editor/designer Chris Sparks on behalf of “Cul de Sac” cartoonist Richard Thompson, who is battling Parkinson’s Disease—a piece of artwork done by Watterson depicting one of Thompson’s Cul de Sac characters sold in 2012 as part of a charity auction to benefit Team Cul de Sac—and the profits from the sale of the original art (Heritage is waiving the seller’s fee on the artwork and will also contribute half of the Buyer’s Premium) will be donated to the Michael J. Fox Foundation for Parkinson’s Research.